The present invention relates to a novel arterial blood sample syringe for use in connection with blood gas analysis. More specifically, the syringe of the present invention is designed to substantially reduce or eliminate error in blood sampling procedures through the use of a preset means that defines the maximum volume of blood that can be delivered to the syringe either by aspiration or by arterial blood pressure. Further, the syringe of the present invention provides improvement in elimination of air contamination in connection with obtaining an arterial blood sample.
Earlier U.S. Pat. No. 4,133,304 discloses an apparatus for obtaining a fixed volume blood sample, which includes a sample gathering capillary tube which is vented by the use of a fibrous thread, which can be removed to seal the capillary tube. The earlier device in one embodiment provides an arrangement for blood aspiration through the use of a piston which surrounds the capillary tube.
The prior art device has a rather complex construction and is difficult to use in connection with some blood-gas analyzing equipment which require that a blood sample be ejected into the analyzing equipment.
Accordingly, it is an object of the present invention to provide a preset fixed maximum volume blood sampling syringe which can be used in either the self-venting mode, wherein a sample is obtained by arterial blood pressure, or in an aspiration mode, wherein blood is drawn by vacuum suction. It is another object of the invention to provide such device which is simple to manufacture and which is capable of easily expelling a blood sample into blood-gas analyzing equipment.